1. Technical Field
The present invention relates to a robot.
2. Related Art
Typically, an industrial robot with an articulated arm is installed on the ground, and for example, is configured in such a manner as to assemble a predetermined structural body on a work bed. The movement envelope of the articulated arm excludes an envelope in which the articulated arm interferes with a base of the industrial robot installed on the ground.
The ceiling mounted robot is an industrial robot, the base of which is installed on a ceiling so as to avoid interference between the articulated arm and the base. This articulated arm can have a wide movement envelope around the base of 360° or greater.
In recent years, attempts have been made to increase the motion speed and reduce the non-operation time of such an industrial robot so as to cope with the demand for productivity improvement in association with the use of the industrial robot. However, a high motion speed increases the amount of heat generation of a drive unit such as a motor, and a reduced non-operation time reduces the cooling time of the drive unit, which is a deficiency. When the temperature of the drive unit increases, and the temperature increase outpaces the heat dissipation capacity of the industrial robot, and exceeds a predetermined reference value for maintaining the performance and the life span of the drive unit, a countermeasure of decreasing the motion speed below the capacity of the industrial robot, or increasing a run-down time is taken.
JP-A-9-323286 discloses a method of cooling a drive motor of an industrial robot. In this method, the motor is attached to a robot main body having thermal conductive properties via a flange, and the motor is in contact with a cover via grease or a plate which has thermal conductive properties. In this configuration, heat generated from the motor is transferred in two heat transfer paths, one of which is a path on which heat is transferred to the robot main body via the flange, and the other of which is a path on which heat is transferred to the robot main body via the cover. Accordingly, it is possible to improve the heat dissipation performance of the motor, that is, the cooling performance.
However, the technology in the related art has the following problem.
The robot may adopt a configuration in which the drive unit such as the motor is supported by an arm, and drives a joint portion of the arm, a working shaft in the arm, and the like. At this time, when a structure is adopted in which heat escapes from the drive unit to the arm, the temperature of the entirety of the arm increases, and the arm extends due to thermal expansion, and the accuracy of motion decreases.